The influence of local actors and socioeconomic constraints on biological invasions is often ignored. Wetland plant harvesters appeared to intentionally influence cattail (Typha domingensis) invasion around Lake Pátzcuaro, México, by altering their harvesting regimes, according to interviews with 44 expert respondents and botanical surveys. The oldest and most experienced harvesters reported controlling Typha initially, sometimes through organized eradication efforts, in order to protect Schoenoplectus californicus, an economically and culturally valuable wetland plant. Later, outsiders commoditized Typha by introducing new weaving designs popular with tourists, while industrial products and new livelihood activities reduced Schoenoplectus harvest. Harvesters from several communities began to promote Typha re-growth. Some harvesters, however, continued to combat Typha to maintain Schoenoplectus production, especially where supply was limited. Interviews suggested novel ecological cause–effect mechanisms and restoration strategies; some local harvesting regimes could efficiently conserve rare plants. An understanding of local ecological knowledge and incentives can inform invasive species control and conservation policy at a broader scale.